As regards the production of snus pouches, the prior art embraces a machine comprising a hopper filled with the tobacco mixture, and rotary conveyor means to which the mixture is released from an outlet of the hopper.
Rotary conveyor means consist in a disc centred on a vertical axis and furnished with peripheral cavities, each containing a portion of tobacco mixture corresponding to the contents of a single pouch.
The single portions are carried by the disc toward an exit or transfer station where they are ejected and thereupon directed along a rectilinear feed duct to a wrapping station; here, the portions of tobacco mixture are packaged in respective pouches.
Alternatively, the conveyor means can take the form of a drum rotatable intermittently about a horizontal axis, on which a continuous stream of tobacco mixture is formed and transported to an exit or transfer station where segments of the stream, corresponding to single portions, are directed into and along the aforementioned rectilinear feed duct to the wrapping station where they are packaged in respective pouches.
The outer surface of the rotating drum presents an annular groove, connected to suction means and accommodating the continuous stream, which is released at the aforementioned transfer station segment by successive segment, each corresponding to a single portion.
In both of the cases described, the transfer of the mixture at the relative station is brought about by pneumatic ejection means, which operate by producing a jet of air such as will distance the portions singly and in succession and feed them along the rectilinear duct.
The duct comprises a funnelform mouth and a rectilinear cylindrical portion.
The wrapping station comprises a tubular mandrel, placed at the outlet end of the rectilinear cylindrical portion, over which a continuous web of wrapping material is formed into a tubular envelope such as can be sealed longitudinally and transversely and then cut, all by conventional methods, so as to obtain a continuous succession of pouches containing the aforementioned portions of tobacco mixture.
It has been found that mixtures adopted for tobacco products of the type in question, by reason of their particular composition, tend to stick and solidify on the various processing and conveying elements of the machine, with the result that frequent servicing is required.
This is a drawback that can bring the machine ultimately to a standstill, and occurs in particular at the restriction presented by the funnelform mouth of the feed duct.
The likelihood of clogging in the duct is increased by the action of the aforementioned pneumatic ejection means, which has the effect of reducing the moisture content of the mixture and causing deposits of the material to dry and harden, so that cleaning operations are made more difficult.